ACC: Weight Loss Plus CPAP Lowers BP

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

A combined intervention of weight loss and continuous positive airway pressure (CPAP) is better at mitigating hypertension in obese patients with obstructive sleep apnea than either therapy on its own, a study found.

Note that patients in both arms of the study that included a weight-loss intervention lost more weight and had greater reductions in body mass index than those who had only CPAP.

SAN FRANCISCO -- A combined intervention of weight loss and continuous positive airway pressure (CPAP) is better at mitigating hypertension in obese patients with obstructive sleep apnea than either therapy on its own, researchers reported here.

In a per-protocol analysis of a secondary study of the COSA trial, patients in the combination arm had a significantly greater reduction in systolic blood pressure compared with those who only had a weight-loss intervention, or only CPAP (-14 mm Hg versus -6 mm Hg and -2 mm Hg, respectively, P<0.05 for both comparisons), according to Julio Chirinos, MD, of the University of Pennsylvania in Philadelphia, and colleagues.

Chirinos reported the findings during a session at the American College of Cardiology meeting here.

Because so many patients with both conditions also have hypertension, "if we diagnose an obese patient with sleep apnea, then not only should we treat the sleep apnea when indicated, but also address the obesity itself, because just eliminating the sleep apnea and leaving the obesity is not going to achieve the amount of benefit in terms of blood pressure that combination therapy with weight loss and CPAP will provide," Chirinos told MedPage Today.

Many studies have established an association with hypertension for both obesity and sleep apnea, but they haven't been able to determine the relative contributions of each to the burden of hypertension.

Trials have looked at the effects of weight loss and CPAP on blood pressure separately, but no trial has examined the incremental benefits of combining those therapies.

"Our approach to causality was that if we can establish an incremental benefit of weight loss and CPAP over CPAP alone, that difference has to be coming from a reduction in obesity," Chirinos explained.

So he and colleagues conducted an ancillary study of the Consequences of Obstructive Sleep Apnea (COSA) trial that randomized 181 patients with obesity and moderate-to-severe obstructive sleep apnea to one of three interventions for a 24-week period: CPAP alone, weight loss alone, or combination therapy with both tools.

The main COSA trial looked at inflammatory and metabolic markers including C-reactive protein (which was the primary endpoint) as well as insulin resistance and dyslipidemia. Chirinos explained that those data are not yet available, and that the blood pressure portion of the trial was a secondary study funded by the American Heart Association.

They conducted both an intention-to-treat (ITT) analysis and a per-protocol analysis of the 136 patients who complied with therapy through the end of the study.

Overall, patients in both arms that included a weight-loss intervention lost more weight and had greater reductions in body mass index (BMI) than those who had only CPAP (P<0.0001 for all).

In the ITT analysis, they found reductions in systolic blood pressure across all three groups without a significant difference between the arms.

However, in the per-protocol analysis, there was a significantly greater reduction in systolic blood pressure in the combination therapy group compared with weight-loss alone or CPAP alone.

"Even in people who complied with monotherapy, we couldn't achieve the reductions in blood pressure that we observed when they got the combination," Chirinos told MedPage Today.

Chirinos also noted that there was a significantly greater reduction in mean arterial pressure with the combination compared with the other two monotherapies in the per-protocol analysis (P<0.05), as well as a trend toward greater improvement in brachial pulse pressure with the combination.

He said the findings "have important implications for cardiovascular risk reduction in this population," but noted that compliance with these interventions could be a challenge, given that there was about a 40% compliance rate in each arm over the course of the study.

"We had a large team of people tracking compliance in real time through an online system, and the CPAP machine gives compliance data that we can track and do weekly calls to the subject so they adhere," Chirinos said. "In the weight-loss arm, we had team of dietitians meeting with participants once a week for the duration of study."

"So this proves the concept, but it's expensive," he said. "Whether it's going to be feasible [in the real world] is still a question."

The blood pressure substudy of the COSA trial was supported by the American Heart Association.

The researchers reported no conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

MedPageToday is a trusted and reliable source for clinical and policy coverage that directly affects the lives and practices of health care professionals.

Physicians and other healthcare professionals may also receive Continuing Medical Education (CME) and Continuing Education (CE) credits at no cost for participating in MedPage Today-hosted educational activities.